Method and apparatus for producting fire extinguishing foam



L. G. M. TIMPSON 2,057,218

EXTINGUIS-HING FOAM METHOD AND APPARATUS FOR PRODUCDIG FIRE Fil ed Aug.50, 1954 Patented Oct. l, 1936 V PATENT OFFICE METHOD AND APPARATUS FORPRODUC- ING FIRE EXTINGUISHING FOAM Lewis G. Morris Timpson, Plainlield,N. a, as-

signor to Pyrene-Minimax Corporation, a corporation of DelawareApplication August 30,

13 Claims.

This invention relates to foam-forming methods and apparatus, andparticularly to methods and apparatus for generating a stream of foamconsisting of relatively stable bubbles, for blanketing fires capable ofsuch treatment, and

extinguishing them principally by excluding oxygen from the seat of theblaze. Heretofore it has been common for this purpose to utilizefoamforming chemicals, which react to form a gas .10 that is thenincorporated in a stream of water with some suitable stabilizing agentto make foam. According to the present invention, however, a verysatisfactory foam may be produced by the use of only water, air and astabilizing agent, al-

though another suitable gas may be substituted in whole or in part forair if desired.

Prior attempts have been made to produce what may be termed air-foam, bythe incorporation of air in watercontaining saponin or a similarstabilizing agent, but these have not proved altogether successful forfire extinguishing purposes due to the difliculty of supplying anadequate quantity of air to a stream of water. It has been found that inattempting to draw air into a flowing stream of water by the movement ofthe stream, as it passes through a jet for example, not more than abouthalf enough air is drawn into a stream of sufficient size for fireextinguishing purposes to produce satisfactoryffoam. Thus a stream ofwater discharged through a jet orifice of a given diameter will presentan outer surface, having an area per lineal inch that is a function ofthe diameter of the stream. The

quantity of air that can be entrained in such a stream is necessarilylimited by this surface area. To visualize this we may consider aflowing stream as having 'a large number of indentations in its surfaceand each of these indentations may be considered to form a pocket toreceive air, much as the buckets of an endless conveyor receive theircharge of material in passing a loading point. Now the stream having thesurface area men-. tioned will have a certain volume or cubical capacityper inch of length that is dependent upon 6 the square of the diameter.The ratio between this volume andthe-surface area specified determinesthe ratio of air to water that will exist in the pipe beyond the pointat which air is sucked into the stream.

0 As stated, this ratio for a jet of suitable diameter for fireextinguishing purposes, say /2 inch,

is such as to produce a very poor grade of foam due to the presence ofonly about half the required amount of air or gas. If the size of thejet :5 is increased the ratio of air to water is even 1934, Serial No.742,041 (01. 261-76) worse. If the jet is decreased in diameter theratio of air to water will be improved, but the resulting stream of foamwill be too small to be effective for fire extinguishing purposes andthe frictional losses in attempting to flow a small 5 stream through apipe or hose will be excessive.

The present invention has for its primary object the production of astable, durable fire extinguishing foam of large volume in relation tothe water used, by the intermingling of'appro- 10 priate proportions ofair or similar gas, water and a stabilizing agent. Toward this end theinvention contemplates so increasing the surface area of a flowingstream of water as to insure entrainment of a suificient amount of airto produce a 5 most satisfactory foam in appropriate quantity to beeffective for fire extinguishing purposes. This may be very effectivelyaccomplished by dividing a stream of water of suitable volume into aplurality of smaller streams, passing each of these 20 separatelythrough a jet arranged to admit air and then merging the streams ofwater and air into a single stream for ultimate distribution. Saponin orother foam stabilizing agent may be introduced in any convenient way,either in advance of the jets or at one or more of the jets.

Other features, objects and advantages will appear from a description ofthe invention, together with the accompanying drawing, in which:

Fig. 1 is a vertical section of an apparatus operso able in accordancewith the present invention; and

Fig. 2 is a transverse section on line 2-2 of Fig. 1.

Before entering upon a description of the par-- ticular apparatuspreferred for the conduct of my process the principles upon which it isconstruct-' ed may be more readily appreciated from the followingconsiderations: It may be assumed that a sufficient volume of water forthe production of 40 fire extinguishing foam will be supplied by a solidstream of 14 mm. diameter. The flow area of such a stream isapproximately 153.9 sq. mm., and the unit surface area will be pi timesthe diameter or approximately 44 sq. mm. per linear 45 mm. If-we dividesuch a stream into six equal cylindrical streams, the flow area of eachwill be 25.65 sq. mm., which means that the diameter of each must be5.71 mm. In other words, at a given velocity of flow, six streams ofwater 5.71 mm. in diameter will deliver thesame volume of water per unittime as one stream of 14 mm. diameter.

. The unit surface area of each is equal to pi times the diameter orsmall stream approximate- 1y 17.94 sq. mm. per linear mm. The combinedunit surface area of all six streams will then be 107.64 sq. mm., ornearly two and one-half times that of the solid 14 mm. stream. Since oneof the six streams is not exposed to the air, the unit surface areaavailable for entraining air is 89.7 sq. mm., slightly more than twicethe unit surface area of the solid 14 mm. stream. It is thus apparentthat by the use of the present invention it is possible to entrain amuch greater volume of air in a given volume of water, and thus producea greater quantity of foam and one having better body.

It should be noted that the above dimensions are not in any waycritical, and a larger or smaller number of streams, or streams ofvarying dimensions, may be used. Likewise it is not necessary to usecylindrical streams, which are specified herein merely for purposes ofillustration.

The apparatus illustrated in the drawing is suitable for carrying outthe present invention, Referring, to Fig. 1, water from any suitablesource, and under suitable pressure, is brought into a jet chamberindicated at H. The chamber In is defined by a bell member l2 and a jetdisc l3, threaded into the mouth of the member 12. A plurality of airejector nozzles M are suitably secured in apertures extending throughpresent instance five nozzles M are arranged in a symmetrical manneraround the center of the disc as illustrated in Fig. 2. Otherarrangements may be employed if desired. In addition to the nozzles- H,a nozzle l5, for use in introducing a stabilizing agent into the stream,and which for convenience will be called a soap ejector nozzle, issimilarly secured centrally of the jet disc IS. A packing gland I50 ispreferably provided around each of the nozzles 14 and I5 and anysuitable means may be employed for preventing leakage between the belll2 and disc l3.

Opposite each of the nozzles a. short distance therefrom, is a receivertogether with its associated nozzle M an ejector for the entrainment ofthe receivers iii are preferably provided with passages having aconstricted portion between flaring portions at the two ends. Thereceivers l6 are secured in suitable apertures of a receiver disc 11,which is supported in the mouth of a bell member I8. The receiver discI! and bell member 18 define a receiver chamber I9. Spacer rods 20connect the jet disc l3 and receiver disc 11, and maintain the nozzlesl4 and receivers IS in proper relationship. If desired the space betweenthe ends of the bells l2 and I8 may be partially enclosed in anysuitable way so long as provision is made for the ready access of air orother gas around the receivers IS.

A receiver 2|, arranged centrally of the receiver disc I? in direct linewith the nozzle l5, differs from the receivers IS in that it is providedvith an enlarged bell end 22, which is adapted to seat within an annularflange 23 formed upon the face of the jet disc l3, thus sealing to theair the ejector formed by the nozzle 15 and receiver ii. A conduit 23 istapped into the bell end 22 of receiver 2!, and is connected to asuitable supply of saponin or other foam-stabilizing agen In theoperation of the apparatus described, .water under suitable pressure isintroduced through the conduit H into the jet chamber l8, from which itissues in six separate jets through the nozzles I4 and i5. As the jetsfrom nozzles H, but spaced I 6, which comprises l through a supplyconduit the jet disc iii. In the l4 pass into their respective receiversl6 they entrain in their exposed surfaces a quantity of air, or suchother gas as surrounds the apparatus. The jet from the nozzle l entrainsand takes up a quantity of saponin or other foamstabilizing agent whichis supplied through conduit 23, and all of the jets are again merged inthe receiver chamber l9. As the stream thus formed flows out through adischarge conduit 24, the gas and stabilizing agent are distributedthroughout the stream, forming a stable foam. It is apparent that thevolume of foam thus formed is greater than would be possible by the useof a single solid jet of water and the absence of excess water lendsbetter body and durability to the foam produced.

While the form of apparatus described in detail is considered thepreferred construction it will be appreciated that various changes maybe made. For example, the foam stabilizing jet might be arranged inadvance of and in series with the group of air jets instead of inparallel therewith or the stabilizer might be added by means of a forcepump on either the high or low side of one or more of the air jets.Furthermore the separate receivers for the jets might be replaced by asingle large receiver.

The terms and expressions employed herein are used for purposes ofdescription and not of limitation. It is recognized that manymodifications of the construction disclosed may be made within the scopeof the present invention as defined by the claims which follow.

What is claimed is:-

1. In apparatus for producing fire extinguishing foam, a plurality ofejectors, means for passing a stream of water through each of saidejectors, means for introducing a foam-stabilizing agent into one ofsaid streams, means for introducing a gas into the remaining of saidstreams by aspiration, and means for merging said streams in a singledischarge conduit.

'2. In apparatus for producing fire extinguishing foam, a jet chamber,means for supplying water to said jet chamber, a plurality of nozzlespiercing a wall of said jet chamber, a receiver chamber, a plurality ofreceivers piercing a wall of said receiver chamber and extending towardsaid nozzles, each of said receivers registering with one of saidnozzles, means for introducing foam stabilizing material into said r:ceiver chamber and a discharge conduit leading from said receiverchamber.

3. In apparatus for producing rlre extinguishing foam, a jet chamber,means for supplying water to said jet chamber, a plurality of nozzlespiercing a wall of said jet chamber, a receiver chamber, a plurality ofreceivers piercing a wall of said receiver chamber and extending toward.said nozzles, each of said receivers registering with one of saidnozzles, means for supplying a foam stabilizing agent to one of saidreceivers, means for supplying a gas to a plurality of said receivers,and a discharge conduit leading from said receiver chamber.

4. In apparatus for producing fire extinguishing foam, a jet chamber,means for supplying water to said jet chamber, a plurality of nozzlespiercing a wall of said jet chamber, a receiver chamber, a plurality ofreceivers piercing a wall of said receiver chamber and extending towardsaid nozzles, each of said receivers registering with one of saidnozzles, means for supplying a foam stabilizing agent tov one of saidreceivers, the remaining receivers being in open communication with theatmosphere, and a discharge conduit leading from said receiver chamber.

5. In apparatus for producing fire extinguishing foam, means forsupplying a stream 01' water, means for dividing said supply stream intoa plurality of secondary streams, means for introducing afoam-stabilizing agent into one of said secondary streams, means forintroducing a gas into others of said secondary streams by aspiration,and means for merging said secondary streams to form a. single dischargestream.

6. In apparatus for producing fire extinguishing foam, means forsupplying a. stream of water, means for dividing said supply stream intoa plurality of secondarystreams, means for supplying a gas undersubstantially atmospheric pressure to the outer surfaces of a number ofsaid secondary streams, means for merging said secondary streams to forma single discharge stream, and means for aspirating a foam stabilizingagent into one of said streams.

7. In apparatus for producing fire extinguishing foam a plurality ofreceivers, means for passing a stream of water through each of saidreceivers, a plurality of said ejectors being arranged to entrain a gasin the outer surfaces of said streams by aspiration, means for mergingthe streams from all of said receivers into a single stream, and meansfor supplying a foam stabilizing agent into the water in one of saidstreams.

8. A method of forming fire extinguishing foam which comprises splittinga flowing stream of water into a plurality of separately confinedsmaller streams, introducing a gas into a number of said streams byaspiration, merging said smaller streams into a single stream, andadding a foam stabilizing agent to said merged stream.

9. A method of forming fire extinguishing foam which comprises splittinga flowing stream of water into a plurality of separately confinedsmaller streams. introducing a gas into a number of said streams by theaction 01' the flow thereof, merging said smaller streams into a singlestream, and adding a foam stabilizing agent to one of said streams.

10. A method of forming fire extinguishing foam which comprisessplitting a flowing stream 01' water into a plurality of smallerstreams, entraining a gas in the outer surfaces of a number 01' saidstreams by aspiration, merging said smaller streams into a, singlestream, and adding a foam stabilizing agent to one of said smallerstreams.

11. The method of forming fire extinguishing foam comprising dividing astream of water into a plurality of smaller streams, aspirating airindependently into a number of said smaller streams, introducing foamstabilizing ingredients into another of said streams, and finally merg-"ing all of said smaller streams into a single large stream.

12. In apparatus for producing fire extinguishing foam, a plurality ofreceivers exposed to the atmosphere, a plurality of nozzles, means forpassing a stream of water through each of said nozzles into saidreceivers, means for merging the resulting streams in a single dischargeconduit. and means for introducing a foam stabilizing agent into saidmerged stream.

13. In apparatus for producing fire extinguishing foam, a plurality ofreceivers exposed to the atmosphere, a. receiver sealed off from theatmos phere, means for passing a stream of water through a separatenozzle into each of said receivers, means for introducing afoam-stabilizing agent into said sealed receiver, and means for mergingthe resulting streams in a single dis charge conduit.

LEwIsG. MORRIS 'rmpson.

